Sound-box for sound recording and reproducing machines



E. R. JOHNSON. SOUND BOX FOR SOUND RECORPINQ AND REPRODUCING MACHINES Rm FM m W P a 3 a 5 E 3 N ATTORNEYS t. H. JOHNSON. soum) BOX FOR soumaRECORDING AND REPRODUCING MACHINES.

' APPLICATION FILED NOV. I2, 19!]. 1,35 3,479. PatentedSept. 21,1920.

3 SHEETS-SHEET 2.

2329.6; q Egg nvvslv TOR ATTORNEYS WITNESS E. R. JOHNSON. SOUND BOX FORSOUND RECORDING AND REPRODUCING MACHINES.

APPLICATION FILED NOV. I2, 1917. I 1,353,479. PatentedSept. 21, 1920.

3 SHEETS-SHEET 3. I

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0 r IIIIIIIIIQ UNITED STATES.

PATENT OFFICE.

ELDRIPGE' R. JOHNSON, F MERION, PENNSYLVANIA, ASSIGNOR TO VICTOR TALKINGMACHINE COMPANY, .A CORPORATION OF NEW JERSEY.

SOUND-BOX FOR SOUND RECORDING AND REPBOD' UCING MACHINES.

Application filed November 12, 1917. Serial No. 201,627.

I T 0 all whom it may concern:

of Pennsylvania, have invented certain new and useful Improvements inSound-Boxes for Sound Becordingand Reproducing Machines, of which thefollowing is a specification.

The object of this inventionis to produce a sound box which is verysensitive, and is equallyresp'onsive to the fine rapid, complex soundvibrations, and to the simple, less frequent or slower vibrations,whereby a true, accurate record of sound vibrations may be produced orreproduced by the use thereof.

Further objects of my invention will appear in the specification andclaims below.

Referring now' to the drawings forming a part of this specification andin' which the same reference letters are used to designate .the sameparts throughout the various views,

Figure 1 ma front elevational view of a sound box embodying myinvention; Fig. 2 is a side elevation of the same; Fig. 3 is a bottomplan view of the same; Fig. 4: is a fragmentary sectional view taken onthe line 4--4= of Fig. 3; Fig. 5 is a fragmentar rear View of the lowerportion of the soun box;

Fig. 6 is a perspective view of one form of the spring member of thestylus bar mounting; Fig. '7 is a fragmentary sectional view showing theway in which the spring member and the stylus bar may be connectedtogether; Fig. 8 is a front elevational View of a modified form of myinvention; Fig. 9 is a side elevational viewof the same; Fig. 10 is abottom plan view of the same; Fig. 11 is a fragmentary sectional Viewtaken on the line 11-11 of Fig. 10; Fig. 12 is a fragmentary rear viewof the lower portion'of the sound box showing the mounting for thestylus bar; Fig. 18 is a detail fragmentary view showing the manner ofattaching the spring members to the stylus bar; Fig.14 is a plan view ofone of the spring members used in the modification shown'in Figs. 8 toline 18-18 of Fig. 17.

In Figs. 1 to 7 is illustrated the preferred form or embodiment of myinvention and therefore the description of the invention will first bedirected particularly thereto.

The sound box'casing comprises a front part or portionl and aback partor portion 2 between which portions the diaphragm 3 is mounted. Thesoundbox back 2- is provided with a rearwardly extending portion 2and with anaperture 4 extending through said back portion 2, and through theprojecting portion 2'. The interior of the opening 4: is provided with apin 5 by meansof which the sound box is secured and positioned withrespect to the'sound, conduit (not shown). The diaphragm 3 within thesound box casing is preferably held in position by two elastic gaskets6--6, but this invention is not to be construed as limited totherparticular form of mounting for the. diaphragm. Thus, another formof gasket is shownin the second and fourth modifications andembodiments'of my invention (see Figs. 11 and 18) in which the gasket isshown as a channeled elastic or resilient an nular member 6, whichyieldingly engages opposite sides of the diaphragm 3.- Any othersuitable form of mounting for the diaphragm may, however, be employed incarrying out the invention of this application.

The stylus bar 7 consists of a pivoted, os-

Patented Sept. 21, 1920.

cillatory member, the upper portion 8 of -7. The upper portion 8 of thestylus bar and the stylus holding portion-10 preferably extend insubstantially parallel directions. They are offset with respect to eachother, and are rigidly connected together by the rigid-web or connection9.

Adjacent the top of the stylus holding portion 10 of the stylus bar 7are preferablv provided a pair of oppositely dlsposed alined membersforming a crossbar 11, on which the stylus bar, as a whole substantiallyvibrates, and to which are attached the spring members for applying thedesired amount of tension to the stylus bar.

The outer ends of the cross bar 11 are respectively provided with flatsurfaces 11'- 11' having kerfs or V-shaped channels 12 extendinglongitudinally thereof. Preferably that portion of the cross bar 11which is adjacent the stylus carrying portion 10 is substantiallycircular in cross-section, and the ends thereof are preferablysubstantially semi-circular in cross-section, providing flat surfaces11-11 which lie in a plane slightly above and parallel to a diameter ofthe said circular portion of the cross bar and normal to the axis of theportion 10 of the stylus bar 7, and the bottoms of the V- shaped groovesare in alinement wlth the axis of the cylindrical portions of the crossbar 11.

The stylus holding portion 10 of the stylus bar 7 is preferably providedwith a socket or recess 13 for the receptlon of the stylus 13' and isfurther provided with a set or binding screw 14 communicating with saidrecess or socket 13, for the purpose of tightly binding or holding thestylus 13' within the socket and thus rigidly uniting the stylus withthe stylus bar.

' V-shaped channels 12 in the flattened sur-- Aportion of the edge ofthe front member 1 of the casing is preferably flattened, and a plate orbase 15 is rigidly secured thereto, as by brazing or soldering, saidplate 15 being provided with a pair of spaced pivot members 16-16, thetop edges of which are V-shaped to form knife edges adapted to be seatedwithin the kerfs or faces l1'11' of the cross bar 11. V

The cylindrical portions of the cross bar on opposite sides of thestylus holding portion 10 are preferably respectively provided with aspring member 17, such as is shown on an enlarged scale in Figs. 6 and7. Said spring members 17 preferably consist of spring steel, and arepreferably provided with straight ends 18 having transverse holes oropenings 19 for the reception of screws 20 by means -of which said endsthereof are rigidly secured to .the cylindrical portions of the crossbar 11. Adjacent said straight ends 18 are curved portions 21,substantially arc-shaped and at the opposite ends of said arc-shapedportions 21, said spring members 17 may be each provided with a secondsubstantially straight portion 22 which may extend substantiallyradially from the center of said arc-shaped portion 21. The ends orportions 22 of said spring members 17 are preferably provided withlongitudinal slots 23 for the reception of adjusting or tensioningscrews 24, pass- 7 ing therethrough and threaded into a suit ableopening therefor in the lugs 25 projecting from opposite edges of theplate 15; The spring members 17 on opposite sides of the stylus holdingportion 10 are preferably oppositely or reversely disposed with respectto each other as clearly illustrated in the drawings, the screws 24 atthe ends 22 thereof being onopposite sides of the axis of oscillation ofthe stylus bar 7.

As constructed and arranged as above set forth, these spring members 17perform the double function of holding the kerfs or channels 12 of thetrunnions or cross bars 11 in firm engagement with the knife edges atthe tops of the pivot members 16,. and of imposing a suitable andadjustable tension on the stylus bar. Then the spring members 17, 17'are rigidly secured to the cross bars or trunnions 11 in the mannerindicated in Fig. 7, and the adjusting screws 24, pass ing through theslots 23, are screwed into the plate 15 as above described, the tensionof the springs is so applied as to firmly hold the knife edges of thesupport 16 in engagement with the kerfs 12 of the trunnions 11, andtheir resiliency permits the stylus bar to vibrate against the tensionof the springs. As all of the members of the mounting of the stylus barare small, and as it is desirable to mount the axis of the stylus barrelatively closely to the casing, the plate 15 may be provided with anopening 26, opposite the head of the screw 20, to prevent any contact orengagement of the head of the screw 20 with the plate 15. The back plate2 maybe provided with a suitable recess 27 within which the screw 24 mayenter. To hold thescrews 24 in any adjusted position, lock nuts 28' maybe provided as clearly shown in Fig. 4. In order that the upper portion8 of the stylus bar may be located relatively near the diaphragm, therim of the front member 1 of the'sound box casing may be provided with asuitable groove or channel 29, to provide clearance between the upperend of the stylus bar and the sound box casing.

bar will both be increased. Asthe adjusting screws are withdrawn, thesaid pressure and tens on are diminished.

Referring to Fig. 7, the substantially cylindrical portion of the crossbar 11 is shown in cross-section and the spring member 17 as attachedthereto. This figure also illustrates particularly the fact that thespring member which,-for convenience may be termed a circular spring,may be secured to the cylindrical portion of the cross bar at anydesired circumferential point thereon dependent upon the purposes to 105From the above it will be seen that the I ment to the cross which thesound box may be adapted to be put. Generally speaking, a cross bar,circular in cross-section,

sired point, and the flat end of the spring may be firmly securedthereto at that point.

Thus, cordance with this invention, the exact point at which a givenspring should be secured to the cross bar to obtain the best reproduc-'tion of sound, may be readily ascertained by experiment and havingfixed that point on a particular cross bar, other stylus bars may bereadily provided with similar springs attached thereto at the samerelative point. If, for any reason, it be desirable to replace a givenspring so mounted on a cylindrical cross bar with another springdifiering from the first in length, resiliency 'or other particular,such new spring may be readily secured to a cylindrical cross bar inanother position circumferentially thereof and best adapted to. such newspring without substantially changing the stylus bar as awhole, exceptas to the providing of a new hole therein for the attachment of the newspring. 1

The portions of the cross bar, embodied in the various modifications inwhich this invention is. shown as embodied, and to which the springs areattached, has been termed substantially cylindrical because it might be,and generally, is desirable to provide it with a limited flat surface11" at the point where a spring member 17 is attached thereto for thepurpose of securing a firm tightclamping of. the spring between the headof the screw 20 and the cross bar. These flattened surfaces 11",however, are limited and, to obtain the full advantages of thecylindrical shape of the cross bar, should be formed after the point atwhich thescrew 20 should be attached has been determined upon. Theproviding of the cylindrieal portions of the cross bar with theselimited flattened surfaces would not, however, substantially interferewith the attachbars of other spring members, like or similar to thespring members 17, at other points thereon and the providing of newflattened surfaces upon which such new springs may be securely fastened.

The oppositely disposed spring members 17 operate to hold the trunnionor cross bar 11 in engagement with the knife edges without exerting anytendency to displace the stylus bar transversely upon its axis upon thepivotal knife edges during the vibration of the stylus bar. The tendencyof one spring to do this is balanced by thetension of the other.Moreover, the curved portions 21 of the springs normally possess centersabout which substantially all distensions or contractions will occur,and these centers of the'curved portions 21 of the springs are may bereadily provided with a tapped radial hole at any de-' in making upsoun'd boxes in -action of the stylus bar so that as the stylus barvibrates, the spring members 17 will substantially coil and uncoil aboutcenters which are for practical purposes coincident with the axisof-oscillation of the stylus bar.

v Ina sound box arranged and constructed as above described, the stylusbar is held upon its pivot members with a definite amount of springpressurewhich remains substantially the same throughout all thefunctionings of the stylus bar. It is also tobe noted that during theoperation of the sound box, that is to say, the vibration of the stylusbar, the extension and contraction of the respective spring members areopposite with respect to each other, that is to' say, while one is beingdistended by the swing of the stylus bar in one direction, the other isbeing retracted. A further feature of the invention resides in the factthat the spring action takes place substantially entirelywithin thecurved portions 21 of the springs. These portions contract and distendwithout any substantial tendency to move, push or slide the free end 22of the spring transversely with respect to-the screw 24. The

motion due to the vibration of the stylus bar is substantially allabsorbed in the curved portions 21 of the springs.

By making the ends 18 of the spring members straight at the point wherethey are attached to thecross bar 11, the curved portions 21 are kept atall times out of actual contact or engagement with the cross bar '11except at the points of their attachment thereto, and any rattle .orother undesirable noise due, to the striking or engagement of theflexible portion 21 of thevsprings against the crossbar is therebyobviated.

-It may here be noted'that while the aopenings 23 in the ends of thespring members 17 are shown as elongated, such. elongation is not forthe purpose of permitting the end 22 to slide transversely with respectto the screw 24 during the operation of the device, but is for the readyassembly of the parts together, irrespective of any slight variations inform or lack of alinement of the individual parts when assembled. Asabove stated, the portion 22 is stationary with respect to the screw 24in so far as any vibrations are concerned. The elongated openings 23also permit the free ends 22 to be adjusted in different positionswithout producing any binding or cramping between the springs and thescrews 24.

In the embodiment of my invention, as illustrated in Figs. 8 to 14,inclusive, the spring member 17' is shown as substantially helical inshape and the middle portion 18 is preferably flattened and is attachedto the trunnion or cross bar 11 by a screw 20. That portion of the crossbar 11 to which this spring is so attached, may be and preferably isprovided with a flattened surface 11", because in this embodiment of theinvention, the point of attachment of the spring to the cross bar ispreferably invariable in the middle of the spring, and at an invariablepoint with respect to the cross 'bar. The outer ends 22' of the spring17, are preferably provided with slots 23 for the reception of suitableadjusting screws 24, threaded into lugs 25 on the face plate 15. Betweenthe flattened portions 18' at the middle of the springs and the ends 22there-' of, these springs are arc-shaped in side elevation on eitherside of said middle por tions and provide curved portions 21 similar tothe curved portion 21 of the spring members 17 shown in Figs. 6 and 7.In this form of the invention, each spring member 17 therefore,substantially encircles the substantially circular portion of the crossbar or trunnion 11 and cooperating with the adjusting screws 24 tends tohold the stylus bar firmly on its knife edge and to apply the desiredtension to the stylus bar under the influence of sound vibration.

In the modification illustrated in Figs. 15 and 16 the construction ofthe mounting for the stylus bar is substantially identical to thatillustrated in Figs. 1 to 7, except that the cross bar or trunnion30 ismounted to oscillate on the adjustable alined pivot pins or screws 31threaded through spaced lugs or projections 16 from the base plate 15,said pivot pins 31 having conical ends firmly seated in conical recessesprovided therefor in the ends of the cross bar 30. Preferably,

- these pivot pins or screws 31 are provided with check nuts 32 tofirmly hold them in their adjusted positions. In this embodiment of myinvention, the spring members 17 operate to apply the desired tension onthe stylus bar but they are not called upon or required to apply atension on the cross bars for the purpose of holding the stylus bar uponknife edge bearings. The pivot pins 31 provide the means for retainingthe stylus bar in a fixed predetermined position with respect to thesound box proper.

The spring members 17 as illustrated in Figs. 15 and 16 are not requiredto apply tension to hold the stylus bar upon its mountings, but theyoperate in other respects in the same manner that the spring members 17do in the form shown in Figs. 1 to 7. By the contraction and expansionof the curved portions 21, they substantially absorb the vibrations ofthe stylus bar and apply the desired tension thereto. When so mountedupon rigid pivot pins 31, a single spring member 17 might in someinstances be employed, provided the free end 22 were rigidy supportedwith respect to the sound box casing. To do this, an additional checknut or binding nut may be provided on the adjusting screw 24 to clampthe free end 22- of the spring firmly between the head of the screw 24and the nut 33.

In the modification shown in Figs. 17 and 18, theopen-sided-bearingsshown and illus trated in connection with Figs. 8 to14, inclusive, are replaced by non-yielding bearings consisting of thealined pivot screws 31, as in the form shown in Figs. 15 and 16, and ifdesired, the free ends 22 of the spring members 17' may also be clampedbetween the heads of the adjusting screw 24 and a nut 33 in the samemanner as that illustrated in Fig. 16.

In this modification also, the springs 17' are employed to impose thenecessary tension upon the stylus bar, but they are not required toexert a pressure on the crossbar for the purpose of holding the crossbar. on knife edge bearings, as the pivotal bearing screws 31 supportthe stylus bar in a fixed predetermined position.

'Briefiy, the spring members or springs 17 shown in the modificationillustrated in Figs. 15 and 16, are like the spring members shown in themodification illustrated in Figs. 1 to 7, and the structure diffeis inthe replacing of the knife ed e or other opensided bearings shown inFigs. 1 to 7 with unyielding pivotal bearings. Similarly, the springmembers 17 of the modification shown in Figs. 17 and 18 are like thespring members shown in Figs. 8 to '14 and the construction merelyinvolves the replacing of the knife edge or other open-sided bear- 100'ings with pivot pins or other unyielding bearings. In the structureshown in Figs.

15 to '18, the spring members operate to tension the stylus bar in thesame manner that the spring members shown in Figs. 1 to 14 impose atension to the stylus bar and the operation of the spring members shownin all the figures, under the influence of the. vibration of thediaphragm, is alike. The motion of the styus bar is modified by thetension of the circularly curved or arcshaped portions of the springmembers as these portions expand and contract somewhat in the mannerthat the hairspring of a balance wheel of a watch coils and uncoils,but, of course, to a much more limited extent.

It is of course to be understood that the invention of this applicationmay be embodied in slightly different constructions over thoseillustrated in the drawings of this application, and the same is'not tobe construed as limited to the exact form or proportions illustrated,for various changes .maybe made without departing from the spirit andscope of this invention.

This application is a continuation in part of a rlor application filedby me May 1,

ent positions to vary the tension 'tively fixed positions whereby saidsty I claim and desire to protect by Letters Patent of the UnitedStates:

tively curved oppositely around the saidpivotal axis of the stylus bar.

2. In'a sound box, the combination of a casing, a stylus bar, a bearingon said casing for said stylus bar, springs attached to said stylus barand each having a portion curved around the axis of oscillation of saidstylus bar, and means to fixedl holdthe free ends of said springs in dierent positions to vary and through said springs to hold said stylus baron said bearing.

3; In a sound box, the combination of a casing, a stylus bar, a'bearingon said casbar, a palr of sprmgs ating for said stylus tached to saidstylus bar and each having a portion spirally curved around the axis ofoscillation of said stylus bar in opposite directions respectively, andmeans to fixedly hold the free ends of said springsin differof saidsprings and said stylus'bar, and through said springs to hold saidstylus bar on said bearing.

4. In asound box,

bearings in which said stylus bar is mounted, a pair of oppositelydisposed spiral springs each being attached to said stylus bar and beingcurved around the axis of oscillation of said stylus bar in oppositedirections respectively, means disposed springs secured to said stylusbar and each comprlsinga. portion substantially spirally curved aboutthe axis of oscillation and means to hold the difli'erent relalus ofsaid stylus bar, free ends of said springs in bar is held on said bearmand the oscillation of said stylus bar 0 the tension of said stylus bar,

y the combination of a casing, a diaphragm, a stylus bar, open sided ycasing, bearings thereon, a stylus for securing said springs to saidcasing to impose a tension on said stylus bar and to hold said ectssubstantially radial distention and contraction of said curved portionsabout tion, and changes in form and osition of said springs, due to theoscillation of said stylus bar, are confined to. said curved portions.

6. In a sound box, the combination of a casing, said stylus barinterposed between said casing and said stylus bar, a pair of oppositelydisposed springs secured to said stylus bar, and each comprising aportion substantially spirally curved about the axis of oscillation ofsaid stylus bar, the center of curvature of said curved portions beingclose to said axis of oscillation, and means tohold the free ends ofsaid springs in different relatively fixed positions whereby said stylusbar is held on said bearings. a

7 .The combination in a sound-box of a casing, a stylus bar mounted foroscillatory movement thereon and a pair of spring members each coiled inopposite directions about the axis of oscillation of the stylus bar, andhaving one end secured to the casing and the opposite end secured to thestylus bar.

8. The combination in a sound box of a casing, a stylus bar mounted foroscillatory movement thereon and oppositely coiled spiral spring membersarranged transversely -to the axis of oscillation. of the stylus bar andsecured at one end to the stylus barf and means for securing theopposite ends 0 said spring members to the casing.

' 9. The combination in a sound box of a bar oscillatably mounted on thebearings, and means for tensioning the stylus bar and retaining the sameon said bearings consisting of oppositely coiled spiral spring membersarranged transversely to the axis of oscillation of the stylus bar andsecured to the stylus bar and to the casing.

10. The combination in a sound box of a casing, a stylus bar mounted foroscillatory movement thereon, arranged transversely'to the-axis ofoscillation of the stylus bar, and means for adjustably securingsaidspring members to the casing.

nwitness whereof, I have hereunto set I'ELDRIDGE R. JoHNsou.

said axis of oscillaa stylus bar, knife edge bearings for stylus bar andsecured to the.

spiral spring members "my hand this 9th day of November, A. D. 1917.

